Dopamine agonists are first line treatment for prolactinomas. This treatment can cause serious complications in patients with invasive macroprolactinomas. This study reviewed 195 patients attending the endocrine clinic and/or undergoing surgery for pituitary tumours at The Royal Melbourne Hospital in a seven-year period (1996-2002). Thirty three patients had macroprolactinoma (diameter >10 mm). Eleven of them were treated with dopamine agonist prior to surgery and four developed severe complications. This study suggests that the severe complications of dopamine agonist therapy may be higher than previously reported. All patients should be educated about these complications and their early recognition.